High stiffness rubber composition

ABSTRACT

The rubber composition comprises at least one resin based: (A1) on at least one aromatic compound comprising at least one aromatic ring bearing at least two functional groups, one of these functional groups being a hydroxymethyl functional group and the other being an aldehyde functional group or a hydroxymethyl functional group; and (A2) on at least one phenolic compound chosen from (A21) at least one aromatic polyphenol comprising at least one aromatic ring bearing at least two hydroxyl functional groups in the meta position with respect to one another, the two positions ortho to at least one of the hydroxyl functional groups being unsubstituted; and/or (A22) at least one aromatic monophenol comprising at least one six-membered aromatic ring bearing a single hydroxyl functional group, the two positions ortho to the hydroxyl functional group being unsubstituted or at least one position ortho to and the position para to the hydroxyl functional group being unsubstituted; and their mixtures.

The invention relates to a rubber composition, to a process for themanufacture of this composition, to a rubber composite and to a tyre.

It is known to use, in some parts of the tyres, rubber compositionsexhibiting a high stiffness during small strains of the tyre. Resistanceto small strains is one of the properties which a tyre has to exhibit inorder to respond to the stresses to which it is subjected.

A high stiffness can be obtained by using a “concentrated” vulcanizationsystem, that is to say comprising in particular relatively high contentsof sulfur and of vulcanization accelerator.

However, such a concentrated vulcanization system is disadvantageous tothe ageing in the raw state of the composition. Thus, when thecomposition is in the form of a semi-finished product, for example of arubber tread, the sulfur may migrate into the surface of thesemi-finished product. This phenomenon, known as blooming, has adetrimental effect on the green tack of the semi-finished product duringthe prolonged storage thereof, with, as consequence, a deterioration inthe adhesion between the semi-finished products during the manufactureof the tyre.

Furthermore, storage of the raw composition containing a concentratedvulcanization system is liable to lead to a reduction in the delay phaseof the composition during the vulcanization thereof, that is to say thetime preceding the start of the vulcanization. Consequently, thecomposition may begin to cure prematurely in certain forming tools andthe vulcanization kinetics are liable to be altered and thevulcanization efficiency to be reduced.

Such a concentrated vulcanization system also detrimentally affects theageing in the cured state. Indeed a deterioration in the mechanicalproperties of the cured composition is observed, in particular at thelimits, for example in the elongation at break.

A high stiffness may otherwise be obtained by increasing the content ofreinforcing filler.

However, in a known way, increasing the stiffness of a rubbercomposition by increasing the content of filler may detrimentally affectthe hysteresis properties and thus the rolling resistance properties oftyres. In point of fact, it is an ongoing aim to lower the rollingresistance of tyres in order to reduce the consumption of fuel and thusto protect the environment.

Finally, a high stiffness can be obtained by incorporating certainreinforcing resins, as disclosed in WO 02/10269.

Conventionally, the increase in the stiffness is obtained byincorporating reinforcing resins based on a methylene acceptor/donorsystem. The terms “methylene acceptor” and “methylene donor” are wellknown to a person skilled in the art and are widely used to denotecompounds capable of reacting together to generate, by condensation, athree-dimensional reinforcing resin which will become superimposed andinterpenetrated with the reinforcing filler/elastomer network, on theone hand, and with the elastomer/sulfur network, on the other hand (ifthe crosslinking agent is sulfur). The methylene acceptor is combinedwith a hardener, capable of crosslinking it or hardening it, alsocommonly known as “methylene donor”. Examples of such a methyleneacceptor and donor are described in WO 02/10269.

The methylene donors conventionally used in rubber compositions fortyres are hexamethylenetetramine (abbreviated to HMT) orhexamethoxymethylmelamine (abbreviated to HMMM or H3M) orhexaethoxymethylmelamine.

The methylene acceptors conventionally used in rubber compositions fortyres are pre-condensed phenolic resins.

However, the combination of phenolic resin, conventionally used asmethylene acceptor, with HMT or H3M as methylene donor producesformaldehyde during the vulcanization of the rubber composition. Inpoint of fact, it is desirable to reduce, indeed even to eliminate, inthe long run, formaldehyde from rubber compositions due to theenvironmental impact of these compounds and the recent developments inregulations, in particular European regulations, relating to this typeof compound.

It is an aim of the invention to provide a rubber composition which isstiffened by means of compounds having a low environmental impact.

To this end, a subject-matter of the invention is a rubber compositioncomprising at least one resin based:

-   -   A1) on at least one aromatic compound comprising at least one        aromatic ring bearing at least two functional groups, one of        these functional groups being a hydroxymethyl functional group        and the other being an aldehyde functional group or a        hydroxymethyl functional group; and    -   A2) on at least one phenolic compound chosen from:        -   A21) at least one aromatic polyphenol comprising at least            one aromatic ring bearing at least two hydroxyl functional            groups in the meta position with respect to one another, the            two positions ortho to at least one of the hydroxyl            functional groups being unsubstituted,        -   A22) at least one aromatic monophenol comprising at least            one six-membered aromatic ring bearing a single hydroxyl            functional group,            -   the two positions ortho to the hydroxyl functional group                being unsubstituted or            -   at least one position ortho to and the position para to                the hydroxyl functional group being unsubstituted,        -   and their mixtures.

Unexpectedly, the Applicants have discovered, during their researchstudies, that the aromatic compounds A1 of the composition according tothe invention make it possible to avoid the production of formaldehyde,unlike conventional methylene donors. The Applicants have discovered,during their research studies, that an aromatic compound comprising atleast two functional groups, including at least one hydroxymethylfunctional group, could, with a phenolic compound, form an alternativeresin to the reinforcing resins based on a methylene acceptor/donorsystem.

In addition, the specific combination of the aromatic compounds A1 andof the phenolic compounds A2 of the composition according to theinvention makes it possible to obtain rubber compositions exhibiting anequivalent, indeed even greatly improved, low-strain stiffness withrespect to conventional rubber compositions which comprise HMT or H3Mmethylene donors and a superior low-strain stiffness with respect to arubber composition devoid of reinforcing resin.

Furthermore, the specific combination of the aromatic compounds A1 andof the phenolic compounds A2 of the composition according to theinvention makes it possible to conceive rubber compositions exhibiting asatisfactory maintenance of stiffness with the increase in thetemperature, in any case better than a rubber composition devoid ofreinforcing resin.

The expression “resin based on” should, of course, be understood asmeaning a resin comprising the mixture and/or the product of thereaction between the various base constituents used for the finalcondensation of this resin, preferably only the product of the reactionbetween the various base constituents used for this resin, it beingpossible for some of them to be intended to react or capable of reactingwith one another or with their immediate chemical surroundings, at leastpartly, during the various phases of the process for the manufacture ofthe composition, of the composites or of the tyre, in particular duringa curing step. Thus, the base constituents are the reactants intended toreact together during the final condensation of the resin and are notreactants intended to react together to form these base constituents.

In accordance with the invention, the base constituents thus comprise atleast one aromatic compound A1 and at least one phenolic compound A2. Inone embodiment, the base constituents can comprise other additionalconstituents different from the aromatic compound A1 and from thephenolic compound A2. In another embodiment, the base constituents areconstituted of at least one aromatic compound A1 and of at least onephenolic compound A2.

Preferably, in the embodiment where the base constituents comprise otheradditional constituents, these other additional constituents are devoidof formaldehyde and/or devoid of methylene donor selected from the groupconsisting of hexamethylenetetramine (HMT), hexamethoxymethylmelamine(H3M), hexaethoxymethylmelamine, lauryloxymethylpyridinium chloride,ethoxymethylpyridinium chloride, polymers of hexamethoxymethylmelamineof trioxane of formaldehyde, hexakis(methoxymethyl)melamine,N,N′,N″-trimethyl-N,N′,N″-trimethylolmelamine, hexamethylolmelamine,N-methylolmelamine, N,N′-dimethylolmelamine,N,N′,N″-tris(methoxymethyl)melamine,N,N′,N″-tributyl-N,N′,N″-trimethylolmelamine. More advantageously, theseother additional constituents are devoid of formaldehyde and devoid ofthe methylene donors described in this paragraph.

More preferably, in the embodiment where the base constituents compriseother additional constituents, these other additional constituents aredevoid of formaldehyde and/or devoid of methylene donor selected fromthe group consisting of hexamethylenetetramine,hexaethoxymethylmelamine, hexamethoxymethylmelamine,lauryloxymethylpyridinium chloride, ethoxymethylpyridinium chloride,hexamethoxymethylmelamine of trioxane and the N-substitutedoxymethylmelamines corresponding to the general formula:

in which Q represents an alkyl group containing from 1 to 8 carbonatoms; F₁, F₂, F₃, F₄ and F₅ are selected, independently of one another,from the group consisting of a hydrogen atom, of an alkyl groupcontaining from 1 to 8 carbon atoms, of the —CH₂OQ group and theircondensation products. More advantageously, these other additionalconstituents are devoid of formaldehyde and devoid of the methylenedonors described in this paragraph.

More preferably still, in the embodiment where the base constituentscomprise other additional constituents, these other additionalconstituents are devoid of formaldehyde and/or devoid of methylenedonor. More advantageously, these other additional constituents aredevoid of formaldehyde and devoid of methylene donors.

Devoid of formaldehyde or devoid of methylene donor is understood tomean that the total content by weight of formaldehyde or of methylenedonor or donors belonging to the groups described above, by total weightof the aromatic compound or compounds A1 in the base constituents, isless than or equal to 10%, preferably less than or equal to 5%, morepreferably less than or equal to 2% and more preferably still less thanor equal to 1%.

Devoid of formaldehyde and devoid of methylene donor is understood tomean that the total content by weight of formaldehyde and of methylenedonor or donors belonging to the groups described above, by total weightof the aromatic compound or compounds A1 in the base constituents, isless than or equal to 10%, preferably less than or equal to 5%, morepreferably less than or equal to 2% and more preferably still less thanor equal to 1%.

“Meta position with respect to one another” will be understood to meanthat the functional groups targeted, for example the hydroxyl functionalgroups in the aromatic polyphenol, are borne by carbons of the aromaticring which are separated from one another by a single other carbon ofthe aromatic ring.

“Para position with respect to one another” will be understood to meanthat the functional groups targeted are opposite one another, that is tosay in the 1 and 4 positions of the 6-membered aromatic ring.Analogously, “the para position” with respect to a functional group is aposition opposite the functional group on the 6-membered aromatic ringbearing the functional group.

“In the ortho position to a functional group” will be understood to meanthe position occupied by the carbon of the aromatic ring which isimmediately adjacent to the carbon of the aromatic ring bearing thefunctional group. Analogously, “the ortho position” with respect to afunctional group is the position adjacent to the functional group on thearomatic ring bearing the functional group.

“Member” of a ring will be understood to mean a constituent atom of thebackbone of the ring. Thus, for example, a benzene ring comprises sixmembers, each member consisting of a carbon atom. In another example, afuran ring comprises five members, four members each consisting of acarbon atom and the remaining member consisting of an oxygen atom.

“CHO” represents the aldehyde functional group.

“CH₂OH” represents the hydroxymethyl functional group.

The “compound A1” denotes, within the context of the invention, thearomatic compound defined in section 1.1.

The “compound A2” denotes, within the context of the invention, thecompound A21 and/or the compound A22.

The “compound A21” denotes, within the context of the invention, thearomatic polyphenol defined in section 1.2.

“Aromatic polyphenol” is understood to mean an aromatic compoundcomprising at least one benzene ring bearing more than one hydroxylfunctional group.

The “compound A22” denotes, within the context of the invention, thearomatic monophenol defined in section 1.2.

Within the context of the invention, the carbon products mentioned inthe description may be of fossil or biosourced origin. In the lattercase, they may partially or completely result from biomass or beobtained from renewable starting materials resulting from biomass.

The rubber composition thus comprises at least one (that is to say, oneor more) crosslinked reinforcing resin, this reinforcing resin beingconstituted by the resin according to the invention; this resin beingbased on at least one (that is to say, one or more) aromatic compound A1and at least one (that is to say, one or more) phenolic compound A2,which constituents will be described in detail below.

Another subject-matter of the invention is a rubber compositioncomprising:

A1) at least one aromatic compound comprising at least one aromatic ringbearing at least two functional groups, one of these functional groupsbeing a hydroxymethyl functional group and the other being an aldehydefunctional group or a hydroxymethyl functional group; andA2) at least one phenolic compound chosen from:

-   -   A21) at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted;    -   A22) at least one aromatic monophenol comprising at least one        six-membered aromatic ring bearing a single hydroxyl functional        group,        -   the two positions ortho to the hydroxyl functional group            being unsubstituted or        -   at least one position ortho to and the position para to the            hydroxyl functional group being unsubstituted;    -   and their mixtures.

Another subject-matter of the invention is a process for the manufactureof a rubber composition in the raw state, comprising a step of mixing:

-   -   A1) at least one aromatic compound comprising at least one        aromatic ring bearing at least two functional groups, one of        these functional groups being a hydroxymethyl functional group        and the other being an aldehyde functional group or a        hydroxymethyl functional group; and    -   A2) at least one phenolic compound chosen from:        -   A21) at least one aromatic polyphenol comprising at least            one aromatic ring bearing at least two hydroxyl functional            groups in the meta position with respect to one another, the            two positions ortho to at least one of the hydroxyl            functional groups being unsubstituted,        -   A22) at least one aromatic monophenol comprising at least            one six-membered aromatic ring bearing a single hydroxyl            functional group,            -   the two positions ortho to the hydroxyl functional group                being unsubstituted or            -   at least one position ortho to and the position para to                the hydroxyl functional group being unsubstituted,        -   their mixtures; and        -   at least one elastomer.

Another subject-matter of the invention is a process for the manufactureof a rubber composition in the cured state, comprising:

-   -   a step of manufacture of a rubber composition in the raw state        comprising a step of mixing:        -   A1) at least one aromatic compound comprising at least one            aromatic ring bearing at least two functional groups, one of            these functional groups being a hydroxymethyl functional            group and the other being an aldehyde functional group or a            hydroxymethyl functional group; and        -   A2) at least one phenolic compound chosen from:            -   A21) at least one aromatic polyphenol comprising at                least one aromatic ring bearing at least two hydroxyl                functional groups in the meta position with respect to                one another, the two positions ortho to at least one of                the hydroxyl functional groups being unsubstituted,            -   A22) at least one aromatic monophenol comprising at                least one six-membered aromatic ring bearing a single                hydroxyl functional group,                -   the two positions ortho to the hydroxyl functional                    group being unsubstituted or                -   at least one position ortho to and the position para                    to the hydroxyl functional group being                    unsubstituted,            -   and their mixtures,    -   then, a step of shaping the rubber composition in the raw state,    -   then, a step of crosslinking, for example by vulcanization or        curing, the rubber composition during which a resin based on the        phenolic compound A2 and on the aromatic compound A1 is        crosslinked.

Preferably, during the mixing step, at least one elastomer is also mixedwith the composition.

Yet another subject-matter of the invention is a rubber compositioncapable of being obtained by a process as described above.

Another subject-matter of the invention is a rubber composite reinforcedwith at least one reinforcing element embedded in a rubber compositionas described above.

Another subject-matter of the invention is a tyre comprising a rubbercomposition as described above or a rubber composite as described above.

Rubber composition is understood to mean that the composition comprisesat least one elastomer or one rubber (the two terms being synonyms) andat least one other component. A rubber composition thus comprises amatrix of elastomer or of rubber in which at least the other componentis dispersed. A rubber composition is in a plastic state in the raw(non-crosslinked) state and in an elastic state in the cured(crosslinked) state but under no circumstances in a liquid state. Arubber composition must not be confused with an elastomer latex, whichis a composition in a liquid state comprising a liquid solvent,generally water, and at least one elastomer or one rubber dispersed inthe liquid solvent so as to form an emulsion. Thus, the rubbercomposition is not an aqueous adhesive composition.

In the present description, unless expressly indicated otherwise, allthe percentages (%) shown are percentages by weight. The acronym “phr”means parts by weight per hundred parts of elastomer.

Furthermore, any interval of values denoted by the expression “between aand b” represents the range of values extending from more than a to lessthan b (that is to say, limits a and b excluded), whereas any intervalof values denoted by the expression “from a to b” means the range ofvalues extending from the limit “a” up to the limit “b” (that is to sayincluding the strict limits “a” and “b”).

I.1—Aromatic Compound A1 of the Rubber Composition

The first essential constituent of the resin is an aromatic compoundcomprising at least one aromatic ring bearing at least two functionalgroups, one of these functional groups being a hydroxymethyl functionalgroup and the other being an aldehyde functional group or ahydroxymethyl functional group. Thus, in accordance with the invention,it is the said aromatic ring which bears hydroxymethyl and aldehydefunctional groups. The compound according to the invention thuscorresponds to the general formula (I):

HO—CH₂—Ar-B  (I)

where Ar represents an aromatic ring and B represents CHO or CH₂OH.

The aromatic ring is advantageously a 5- or 6-membered ring comprising,as members, carbon atoms and optionally one or more heteroatoms, inparticular nitrogen, oxygen or sulfur atoms, optionally oxidized in theN-oxide or S-oxide form. In one alternative form, the aromatic ringcomprises 0, 1 or 2 heteroatom(s). The remainder of the aromatic ringcan be substituted or unsubstituted.

The aromatic ring can bear 0, 1 or 2 aldehyde functional groups,advantageously 0 or 1 aldehyde functional group.

The aromatic ring can bear 1, 2 or 3 hydroxymethyl functional groups,advantageously 1 or 2 hydroxymethyl functional groups.

In addition, the aromatic ring can also bear 0, 1 or 2 other functionalgroup(s), in particular hydroxyl functional group(s).

In the embodiment in which the aromatic ring is a 6-membered ring, the Band hydroxymethyl functional groups are advantageously in the meta orpara position with respect to one another.

In the embodiment in which the aromatic ring is a 5-membered ring, thering can comprise one or more heteroatoms, in particular nitrogen,oxygen or sulfur atoms, optionally oxidized in the N-oxide or S-oxideform. Advantageously, the aromatic ring comprises 1 or 2 heteroatom(s),preferably 1 heteroatom.

In this embodiment, in which the aromatic ring is a 5-membered ring, atleast one of the three following conditions is met:

-   -   the aromatic ring comprises 0 or a single aldehyde functional        group;    -   the aromatic ring comprises one or two hydroxymethyl functional        groups;    -   apart from the aldehyde and hydroxymethyl functional groups, the        remainder of the aromatic ring is unsubstituted.

Advantageously, these three conditions are met.

In a first case, the aromatic ring comprises:

-   -   a single aldehyde functional group;    -   a single hydroxymethyl functional group;    -   apart from the aldehyde and hydroxymethyl functional groups, the        remainder of the aromatic ring is unsubstituted.

In a second case, the aromatic ring comprises:

-   -   0 aldehyde functional group;    -   two hydroxymethyl functional groups;    -   apart from the hydroxymethyl functional groups, the remainder of        the aromatic ring is unsubstituted.

Advantageously, the compound is of general formula (II):

in which B represents CHO or CH₂OH, X represents O, NR₁, NO, S, SO, SO₂or SR₂R₃, R₁ represents a hydrogen or an alkyl, aryl, arylalkyl,alkylaryl or cycloalkyl group and R₂ and R₃ each represent,independently of one another, a hydrogen or an alkyl, aryl, arylalkyl,alkylaryl or cycloalkyl group.

Advantageously, the compound is of general formula (II):

in which X and B are as defined above.

According to a particularly advantageous embodiment, B represents CHO.In another embodiment, B represents CH₂OH.

According to a preferred embodiment, X represents 0.

In one alternative form, the compound is of formula (IIa):

B being as defined above,and more particularly of formula (II′a1) or (II′a2):

5-(Hydroxymethyl)furfural (II′a1) is a particularly suitable aldehyde,given that this organic compound can be readily derived from renewableresources. Specifically, it is derived in particular from thedehydration of certain sugars, such as fructose, glucose, sucrose,cellulose and inulin.

In another embodiment, X represents NR₁ or NO, advantageously NR₁. R₁ isas defined above.

In one alternative form, the compound is of formula (IIb):

B being as defined above,and more particularly of formula (II′b1) or (II′b2):

in which R₁ represents a hydrogen or an alkyl, aryl, arylalkyl,alkylaryl or cycloalkyl group. Advantageously, R₁ represents a hydrogenor a C₁-C₆ alkyl group.

In another embodiment, X represents S, SO, SO₂ or SR₂R₃.

In one alternative form, the compound is of formula (IIc):

B being as defined above,

with X represents S, SR₂R₃, SO or SO₂ and R₂ and R₃ each represent,independently of one another, a hydrogen or an alkyl, aryl, arylalkyl,alkylaryl or cycloalkyl group, B being as defined above;and more particularly of formula (II′c1) or (II′c2):

in which X represents S, SR₂R₃, SO or SO₂ and R₂ and R₃ each represent,independently of one another, a hydrogen or an alkyl, aryl, arylalkyl,alkylaryl or cycloalkyl group.

The compound can thus be:

Advantageously, R₂ and R₃ each represent, independently of one another,a C₁-C₆ alkyl radical.

The compound is advantageously of formula (II′c1) or (II′c2).

In another alternative form, the aromatic ring is a 6-membered ring,which can comprise 0, one or more heteroatoms, in particular nitrogen,optionally oxidized in the N-oxide form. In one alternative form, thearomatic ring comprises 0, 1 or 2 heteroatom(s).

The B and hydroxymethyl functional groups are advantageously in the metaor para position with respect to one another.

The aromatic ring can bear 0, 1 or 2 aldehyde functional groups,advantageously 0 or 1 aldehyde functional group.

The aromatic ring can bear 1, 2 or 3 hydroxymethyl functional groups,advantageously 1 or 2 hydroxymethyl functional groups.

In addition, the aromatic ring can also bear 0, 1 or 2 other functionalgroup(s), in particular hydroxyl functional group(s).

Advantageously, the compound is of general formula (III):

in which X represents C or NR₁, n has the value 0, 1 or 2, m has thevalue 0 or 1 and p has the value 1, 2 or 3. R₁ represents a hydrogen oran alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group. In accordancewith the invention, p+n>1 with p>0.

Advantageously, R₁ represents a hydrogen or a C₁-C₆ alkyl group.

In one alternative form, n has the value 1, m has the value 0 and p hasthe value 1.

In another alternative form, n has the value 1, m has the value 1 and phas the value 1.

In another alternative form, n has the value 2, m has the value 1 and phas the value 1.

In another alternative form, n has the value 1, m has the value 1 and phas the value 2.

In another alternative form, n has the value 0, m has the value 0 and phas the value 2.

In another alternative form, n has the value 0, m has the value 1 and phas the value 2.

In another alternative form, n has the value 1, m has the value 1 and phas the value 2.

In another alternative form, n has the value 0, m has the value 1 and phas the value 3.

Preferably, the aromatic ring of the compound of formula (III) is abenzene ring. More preferably, this compound of formula (III) isselected from the group consisting of2-(hydroxymethyl)benzene-1-carboxaldehyde,3-(hydroxymethyl)benzene-1-carboxaldehyde,4-(hydroxymethyl)benzene-1-carboxaldehyde,3-hydroxymethyl-6-hydroxybenzene-1-carboxaldehyde,3-hydroxymethyl-4-hydroxybenzene-1-carboxaldehyde,3-hydroxymethyl-2-hydroxybenzene-1-carboxaldehyde,3-hydroxymethyl-2-hydroxybenzene-1,5-dicarboxaldehyde,5-hydroxymethyl-2-hydroxybenzene-1,3-dicarboxaldehyde,3,5-dihydroxymethyl-4-hydroxybenzene-1-carboxaldehyde,3,5-dihydroxymethyl-2-hydroxybenzene-1-carboxaldehyde,1,2-dihydroxymethylbenzene, 1,3-dihydroxymethylbenzene,1,4-dihydroxymethylbenzene, 1,3-dihydroxymethyl-6-hydroxybenzene,1,3-dihydroxymethyl-4-hydroxybenzene,1,3-dihydroxymethyl-2-hydroxybenzene,1,3,5-trihydroxymethyl-2-hydroxybenzene,1,3-dihydroxymethyl-6-hydroxybenzene,1,3,5-trihydroxymethyl-4-hydroxybenzene,1,3,2-trihydroxymethyl-2-hydroxybenzene and the mixtures of thesecompounds.

More preferably still, the aromatic compound used is1-(hydroxymethyl)benzene-4-carboxaldehyde of formula (IIIa) or1,4-dihydroxymethylbenzene of formula (IIIb):

Preferably, the composition is devoid of formaldehyde and/or devoid ofmethylene donor selected from the group consisting ofhexamethylenetetramine (HMT), hexamethoxymethylmelamine (H3M),hexaethoxymethylmelamine, lauryloxymethylpyridinium chloride,ethoxymethylpyridinium chloride, polymers of hexamethoxymethylmelamineof trioxane of formaldehyde, hexakis(methoxymethyl)melamine,N,N′,N″-trimethyl-N,N′,N″-trimethylolmelamine, hexamethylolmelamine,N-methylolmelamine, N,N′-dimethylolmelamine,N,N′,N″-tris(methoxymethyl)melamine,N,N′,N″-tributyl-N,N′,N″-trimethylolmelamine. More advantageously, thecomposition is devoid of formaldehyde and devoid of the methylene donorsdescribed in this paragraph.

More preferably, the composition is devoid of formaldehyde and/or devoidof methylene donor selected from the group consisting ofhexamethylenetetramine, hexaethoxymethylmelamine,hexamethoxymethylmelamine, lauryloxymethylpyridinium chloride,ethoxymethylpyridinium chloride, hexamethoxymethylmelamine of trioxaneand the N-substituted oxymethylmelamines corresponding to the generalformula:

in which Q represents an alkyl group containing from 1 to 8 carbonatoms; F₁, F₂, F₃, F₄ and F₅ are selected, independently of one another,from the group consisting of a hydrogen atom, of an alkyl groupcontaining from 1 to 8 carbon atoms, of the —CH₂OQ group and theircondensation products. More advantageously, the composition is devoid offormaldehyde and devoid of the methylene donors described in thisparagraph.

More preferably still, the composition is devoid of formaldehyde and/ordevoid of methylene donor. More advantageously, the composition isdevoid of formaldehyde and devoid of methylene donors.

Devoid of formaldehyde or devoid of methylene donor is understood tomean that the total content by weight of formaldehyde or of methylenedonor or donors belonging to the groups described above, by total weightof the aromatic compound or compounds A1 in the composition, is lessthan or equal to 10%, preferably less than or equal to 5%, morepreferably less than or equal to 2% and more preferably still less thanor equal to 1%.

Devoid of formaldehyde and devoid of methylene donor is understood tomean that the total content by weight of formaldehyde and of methylenedonor or donors belonging to the groups described above, by total weightof the aromatic compound or compounds A1 in the composition, is lessthan or equal to 10%, preferably less than or equal to 5%, morepreferably less than or equal to 2% and more preferably still less thanor equal to 1%.

I.2—Phenolic Compound A2 of the Rubber Composition: Aromatic Polyphenoland/or Aromatic Monophenol—Compounds A21 and/or A22

In one embodiment, the second essential constituent of the resin is anaromatic polyphenol A21 comprising one or more aromatic ring(s). Thearomatic polyphenol comprises at least one aromatic ring bearing atleast two hydroxyl functional groups in the meta position with respectto one another, the two positions ortho to at least one of the hydroxylfunctional groups being unsubstituted.

In another embodiment, the second essential constituent of the resin isan aromatic monophenol A22 comprising at least one six-membered aromaticring bearing a single hydroxyl functional group. On this aromaticmonophenol, the two positions ortho to the hydroxyl functional group areunsubstituted, or else at least one position ortho to and the positionpara to the hydroxyl functional group are unsubstituted.

In yet another embodiment, the second essential constituent is a mixtureof the aromatic polyphenol A21 and of the aromatic monophenol A22 as aredescribed above.

In accordance with the invention, the compound A21 can be, in oneembodiment, a simple molecule of aromatic polyphenol comprising one ormore aromatic rings, at least one of these aromatic rings, indeed eveneach aromatic ring, bearing at least two hydroxyl functional groups inthe meta position with respect to one another, the two positions orthoat least one of the hydroxyl functional groups being unsubstituted.

Analogously, the compound A22 can be, in one embodiment, a simplemolecule of aromatic monophenol comprising one or more six-memberedaromatic rings, at least one of these six-membered aromatic rings,indeed even each six-membered aromatic ring, bearing a single hydroxylfunctional group, the two positions ortho to the hydroxyl functionalgroup are unsubstituted, or else at least one position ortho to and theposition para to the hydroxyl functional group are unsubstituted.

Such simple molecules do not comprise a repeat unit.

In accordance with the invention, the compound A21 can be, in anotherembodiment, a pre-condensed resin based:

-   -   on at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted; and    -   on at least one compound capable of reacting with the polyphenol        comprising at least one aldehyde functional group and/or at        least one compound capable of reacting with the polyphenol        comprising at least two hydroxymethyl functional groups borne by        an aromatic ring.

Such a pre-condensed resin based on aromatic polyphenol is in accordancewith the invention and comprises, unlike the simple molecule describedabove, a repeat unit. In the case in point, the repeat unit comprises atleast one aromatic ring bearing at least two hydroxyl functional groupsin the meta position with respect to one another.

Analogously and in accordance with the invention, the compound A22 canbe, in another embodiment, a pre-condensed resin based:

-   -   on at least one aromatic monophenol comprising at least one        six-membered aromatic ring bearing a single hydroxyl functional        group:        -   the two positions ortho to the hydroxyl functional group are            unsubstituted, or        -   at least one position ortho to and the position para to the            hydroxyl functional group are unsubstituted;    -   on at least one compound capable of reacting with the monophenol        comprising at least one aldehyde functional group and/or at        least one compound capable of reacting with the monophenol        comprising at least two hydroxymethyl functional groups borne by        an aromatic ring.

Such a pre-condensed resin based on aromatic monophenol is in accordancewith the invention and comprises, unlike the simple molecule describedabove, a repeat unit. In the case in point, the repeat unit comprises atleast one six-membered aromatic ring bearing a single hydroxylfunctional group.

In another embodiment, the compound A21 is a mixture of an aromaticpolyphenol forming a simple molecule and of a pre-condensed resin basedon aromatic polyphenol.

In another embodiment, the compound A22 is a mixture of an aromaticmonophenol forming a simple molecule and of a pre-condensed resin basedon aromatic monophenol.

In the specific embodiments which follow, the aromatic ring(s) of thearomatic polyphenol and/or of the aromatic monophenol are described. Forthe sake of clarity, the “aromatic polyphenol” and/or the “aromaticmonophenol” is/are described therein in its simple molecule form. Thisaromatic polyphenol and/or this aromatic monophenol can subsequently becondensed and will in part define the repeat unit. The characteristicsof the pre-condensed resin are described in more detail subsequently.

Aromatic Polyphenol A21

In a preferred embodiment, the aromatic ring of the aromatic polyphenolbears three hydroxyl functional groups in the meta position with respectto one another.

Preferably, the two positions ortho to each hydroxyl functional groupare unsubstituted. This is understood to mean that the two carbon atomslocated on either side of (in the position ortho to) the hydroxylatedcarbon atom (i.e. bearing the hydroxyl functional group) bear a simplehydrogen atom.

More preferably still, the remainder of the aromatic ring of thearomatic polyphenol is unsubstituted. This is understood to mean thatthe other carbon atoms of the remainder of the aromatic ring (thoseother than the carbon atoms bearing the hydroxyl functional groups) beara simple hydrogen atom.

In one embodiment, the aromatic polyphenol comprises several aromaticrings, at least two of them each bearing at least two hydroxylfunctional groups in the meta position with respect to one another, thetwo positions ortho to at least one of the hydroxyl functional groups ofat least one aromatic ring being unsubstituted.

In a preferred embodiment, at least one of the aromatic rings of thearomatic polyphenol bears three hydroxyl functional groups in the metaposition with respect to one another.

Preferably, the two positions ortho to each hydroxyl functional group ofat least one aromatic ring are unsubstituted.

More preferably still, the two positions ortho to each hydroxylfunctional group of each aromatic ring are unsubstituted.

More preferably still, the remainder of each of the aromatic rings isunsubstituted. This is understood to mean that the other carbon atoms ofthe remainder of each aromatic ring (those other than the carbon atomsbearing the hydroxyl functional groups or bearing the group connectingthe aromatic rings together) bear a simple hydrogen atom.

Advantageously, the aromatic ring bearing at least two hydroxylfunctional groups in the meta position with respect to one another, thetwo positions ortho to at least one of the hydroxyl functional groupsbeing unsubstituted, is a benzene ring.

Advantageously, each aromatic ring of the aromatic polyphenol is abenzene ring.

Mention may in particular be made, as example of aromatic polyphenolcomprising just one aromatic ring, of resorcinol and phloroglucinol as areminder of expanded formulae (IV) and (V):

By way of examples, in the case where the aromatic polyphenol comprisesseveral aromatic rings, at least two of these aromatic rings, which areidentical or different, are selected from those of general formulae:

in which the Z₁ and Z₂ symbols, which are identical or different, ifthere are several of them on the same aromatic ring, represent an atom(for example carbon, sulfur or oxygen) or a connecting group, bydefinition at least divalent, which connects at least these two aromaticrings to the remainder of the aromatic polyphenol.

Another example of aromatic polyphenol is 2,2′,4,4′-tetrahydroxydiphenylsulfide of following expanded formula (VII):

Another example of aromatic polyphenol is2,2′,4,4′-tetrahydroxybenzophenone of following expanded formula (VIII):

It is noted that each compound VII and VIII is an aromatic polyphenolcomprising two aromatic rings (of formulae VI-c), each of which bears atleast two (in the case in point two) hydroxyl functional groups in themeta position with respect to one another.

It is noted, in the case of an aromatic polyphenol comprising at leastone aromatic ring in accordance with the formula VI-b, that the twopositions ortho to each hydroxyl functional group of at least onearomatic ring are unsubstituted. In the case of an aromatic polyphenolcomprising several aromatic rings in accordance with the formula VI-b,the two positions ortho to each hydroxyl functional group of eacharomatic rings are unsubstituted.

According to one embodiment of the invention, the aromatic polyphenol isselected from the group consisting of resorcinol (IV), phloroglucinol(V), 2,2′,4,4′-tetrahydroxydiphenyl sulfide (VII),2,2′,4,4′-tetrahydroxybenzophenone (VIII), resins pre-condensed from atleast one of these phenols and the mixtures of these compounds. In aparticularly advantageous embodiment, the aromatic polyphenol isphloroglucinol.

In one embodiment, the compound A21 comprises a pre-condensed resinbased on the aromatic polyphenol as described in any one of theseembodiments.

This pre-condensed resin is advantageously based:

-   -   on at least one aromatic polyphenol as defined above, and        preferably selected from the group consisting of resorcinol        (IV), phloroglucinol (V), 2,2′,4,4′-tetrahydroxydiphenyl        sulphide (VII), 2,2′,4,4′-tetrahydroxybenzophenone (VIII) and        their mixtures; and    -   on at least one compound capable of reacting with the polyphenol        comprising at least one aldehyde functional group and/or at        least one compound capable of reacting with the polyphenol        comprising at least two hydroxymethyl functional groups borne by        an aromatic ring.

The compound capable of reacting with the polyphenol comprising at leastone aldehyde functional group and/or the compound capable of reactingwith the polyphenol comprising at least two hydroxymethyl functionalgroups borne by an aromatic ring and can be an aromatic compound A1 asdefined above in paragraph 1.1, a compound of formula Ar-(CHO)₂, whereAr is as defined above for the aromatic compound A1 of paragraph 1.1, orany other aldehyde. Advantageously, the said compound capable ofreacting with the polyphenol comprising at least one aldehyde functionalgroup and/or the said compound capable of reacting with the polyphenolcomprising at least two hydroxymethyl functional groups borne by anaromatic ring is selected from the group consisting of an aromaticcompound comprising an aromatic ring bearing at least two functionalgroups, one of these functional groups being a hydroxymethyl functionalgroup and the other being an aldehyde functional group or ahydroxymethyl functional group, formaldehyde, benzaldehyde,furfuraldehyde, 2,5-furandicarboxaldehyde, 1,4-benzenedicarboxaldehyde,1,3-benzenedicarboxaldehyde, 1,2-benzenedicarboxaldehyde and themixtures of these compounds. Very advantageously, when the compound isan aromatic compound comprising an aromatic ring bearing at least twofunctional groups, one of these functional groups being a hydroxymethylfunctional group and the other being an aldehyde functional group or ahydroxymethyl functional group, this compound is selected from the groupconsisting of 5-(hydroxymethyl)furfural, 2,5-di(hydroxymethyl)furan andthe mixtures of these compounds.

Thus, in the pre-condensed resin based on aromatic polyphenol, therepeat unit meets the characteristics of the aromatic polyphenol whichare defined above, with the exception that at least one of the carbonatoms of the aromatic ring, which was unsubstituted, is connected toanother unit.

Whatever the compound other than the aromatic polyphenol at the basis ofthe pre-condensed resin, this pre-condensed resin is devoid of freeformaldehyde. Indeed, even in the case where the pre-condensed resin isbased on an aromatic polyphenol as described above and on formaldehyde,since the formaldehyde has already reacted with the aromatic polyphenol,the pre-condensed resin is devoid of free formaldehyde liable to be ableto react with a compound A1 in accordance with the invention in asubsequent step.

The compound A21 can also comprise a mixture of a free molecule ofaromatic polyphenol and of a pre-condensed resin based on aromaticpolyphenol, as described above. In particular, the compound A21 can alsocomprise a mixture of phloroglucinol and of a pre-condensed resin basedon phloroglucinol.

Aromatic Monophenol A22

The monophenol A22 can be in accordance with two alternative forms. Inone alternative form, the two positions ortho to the hydroxyl functionalgroup are unsubstituted. In another alternative form, at least oneposition ortho to and the position para to the hydroxyl functional groupare unsubstituted.

Advantageously, in the alternative form in which at least one positionortho to and the position para to the hydroxyl functional group areunsubstituted, a single ortho position is unsubstituted and the positionpara to the hydroxyl functional group is unsubstituted.

Preferably, whatever the alternative form, the two positions ortho tothe hydroxyl functional group are unsubstituted. This is understood tomean that the two carbon atoms located on either side of (in theposition ortho to) the hydroxylated carbon atom (i.e. bearing thehydroxyl functional group) bear a simple hydrogen atom.

More preferably still, the remainder of the aromatic ring isunsubstituted. This is understood to mean that the other carbon atoms ofthe remainder of the aromatic ring (those other than the carbon atomsbearing the hydroxyl functional groups) bear a simple hydrogen atom.

In one embodiment, the aromatic monophenol comprises severalsix-membered aromatic rings, at least two of them each bearing a singlehydroxyl functional group and, for at least one of the hydroxylfunctional groups, the two positions ortho to the hydroxyl functionalgroup are unsubstituted, or at least one position ortho to and theposition para to the hydroxyl functional group are unsubstituted.

Preferably, the two positions ortho to each hydroxyl functional group ofat least one six-membered aromatic ring are unsubstituted.

More preferably still, the two positions ortho to each hydroxylfunctional group of each six-membered aromatic ring are unsubstituted.

More preferably still, the remainder of each of the aromatic rings isunsubstituted. This is understood to mean that the other carbon atoms ofthe remainder of each aromatic ring (those other than the carbon atomsbearing the hydroxyl functional groups or bearing the group whichconnects the aromatic rings together) bear a simple hydrogen atom.

Advantageously, the or each aromatic ring of the aromatic monophenol isa benzene ring.

Preferably, the aromatic monophenol is selected from the groupconsisting of phenol, ortho-cresol, meta-cresol, para-cresol,ortho-chlorophenol, meta-chlorophenol, para-chlorophenol,2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid,4-vinylphenol, 4-ethylphenol, 4-isopropylphenol, 4-isobutylphenol,para-coumaric acid and the mixtures of these compounds.

In one embodiment, the compound A22 comprises a pre-condensed resinbased on the aromatic monophenol as described in any one of theseembodiments.

This pre-condensed resin is advantageously based:

-   -   on at least one aromatic monophenol as defined above, and        preferably selected from the group consisting of phenol,        ortho-cresol, meta-cresol, para-cresol, ortho-chlorophenol,        meta-chlorophenol, para-chlorophenol, 2-hydroxybenzoic acid,        3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 4-vinylphenol,        4-ethylphenol, 4-isopropylphenol, 4-isobutylphenol,        para-coumaric acid and the mixtures of these compounds; and    -   on at least one compound capable of reacting with the monophenol        comprising at least one aldehyde functional group and/or at        least one compound capable of reacting with the monophenol        comprising at least two hydroxymethyl functional groups borne by        an aromatic ring.

The compound capable of reacting with the monophenol comprising at leastone aldehyde functional group and/or the compound capable of reactingwith the monophenol comprising at least two hydroxymethyl functionalgroups borne by an aromatic ring and reacting with the said aromaticmonophenol can be an aromatic compound A1 as defined above in paragraph1.1, a compound of formula Ar-(CHO)₂, where Ar is as defined above forthe aromatic compound A1 of paragraph 1.1, or any other aldehyde.Advantageously, the said compound capable of reacting with themonophenol comprising at least one aldehyde functional group and/or thesaid compound capable of reacting with the monophenol comprising atleast two hydroxymethyl functional groups borne by an aromatic ring isselected from the group consisting of an aromatic compound comprising anaromatic ring bearing at least two functional groups, one of thesefunctional groups being a hydroxymethyl functional group and the otherbeing an aldehyde functional group or a hydroxymethyl functional group,formaldehyde, benzaldehyde, furfuraldehyde, 2,5-furandicarboxaldehyde,1,4-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde,1,2-benzenedicarboxaldehyde and the mixtures of these compounds. Veryadvantageously, when the compound is an aromatic compound comprising anaromatic ring bearing at least two functional groups, one of thesefunctional groups being a hydroxymethyl functional group and the otherbeing an aldehyde functional group or a hydroxymethyl functional group,this compound is selected from the group consisting of5-(hydroxymethyl)furfural, 2,5-di(hydroxymethyl)furan and the mixturesof these compounds.

Thus, in the pre-condensed resin based on aromatic monophenol, therepeat unit meets the characteristics of the aromatic monophenol whichare defined above, with the exception that at least one of the carbonatoms of the six-membered aromatic ring, which was unsubstituted, isconnected to another unit.

Whatever the compound other than the aromatic monophenol at the basis ofthe pre-condensed resin, this pre-condensed resin is devoid of freeformaldehyde. Indeed, even in the case where the pre-condensed resin isbased on an aromatic monophenol as described above and on formaldehyde,since the formaldehyde has already reacted with the aromatic monophenol,the pre-condensed resin is devoid of free formaldehyde liable to be ableto react with a compound A1 in accordance with the invention in asubsequent step.

The compound A22 can also comprise a mixture of a free molecule ofaromatic monophenol and of a pre-condensed resin based on aromaticmonophenol, as described above. In particular, the compound A22 can alsocomprise a mixture of phenol and of a pre-condensed resin based onphenol.

Rubber Composition According to the Invention

In some embodiments, depending on the use of the composition, use willbe made of an amount of aromatic compound A1 ranging from 0.1 to 30 phr.Likewise, use will be made of an amount of phenolic compound A2 rangingfrom 0.1 to 30 phr.

In some embodiments, the [aromatic compound A1]:[phenolic compound A2]molar ratio advantageously varies from 3:1 to 1:1, advantageously from3:1 to 1.5:1.

Depending on the use which is made of the composition, the rubbercomposition exhibits, in the cured state, a secant modulus at 10%elongation, MA10, measured according to Standard ASTM D 412 of 1998(test specimen C), of greater than or equal to MPa, preferably ofgreater than or equal to 20 MPa, preferentially of greater than or equalto 30 MPa, more preferably of greater than or equal to 40 MPa and morepreferably still of greater than or equal to 60 MPa.

Preferably, the rubber composition comprises a diene elastomer.

Elastomer or rubber (the two terms being synonyms) of the “diene” typeis understood to mean, generally, an elastomer resulting, at least inpart (i.e., a homopolymer or a copolymer), from diene monomers (monomersbearing two conjugated or unconjugated carbon-carbon double bonds).

Particularly preferably, the diene elastomer of the rubber compositionis selected from the group consisting of polybutadienes (BRs), syntheticpolyisoprenes (IRs), natural rubber (NR), butadiene copolymers, isoprenecopolymers and the mixtures of these elastomers. Such copolymers aremore preferably selected from the group consisting of butadiene/styrenecopolymers (SBRs), isoprene/butadiene copolymers (BIRs),isoprene/styrene copolymers (SIRs), isoprene/butadiene/styrenecopolymers (SBIRs) and the mixtures of such copolymers.

The rubber compositions can contain just one diene elastomer or amixture of several diene elastomers, it being possible for the dieneelastomer or elastomers to be used in combination with any type ofsynthetic elastomer other than a diene elastomer, indeed even withpolymers other than elastomers, for example thermoplastic polymers.

Preferably, the rubber composition comprises a reinforcing filler.

When a reinforcing filler is used, use may be made of any type ofreinforcing filler known for its abilities to reinforce a rubbercomposition which can be used for the manufacture of tyres, for examplean organic filler, such as carbon black, a reinforcing inorganic filler,such as silica, or else a blend of these two types of filler, inparticular a blend of carbon black and silica.

All the carbon blacks conventionally used in tyres (“tyre-grade” blacks)are suitable as carbon blacks. Mention will more particularly be made,for example, of the reinforcing carbon blacks of the 100, 200 or 300series (ASTM grades).

In the case of the use of carbon blacks with an isoprene elastomer, thecarbon blacks might, for example, be already incorporated in theisoprene elastomer in the form of a masterbatch (see, for example,Applications WO 97/36724 or WO 99/16600).

Mention may be made, as examples of organic fillers other than carbonblacks, of functionalized polyvinylaromatic organic fillers, such as aredescribed in Applications WO-A-2006/069792 and WO-A-2006/069793.

“Reinforcing inorganic filler” should be understood, in the presentpatent application, by definition, as meaning any inorganic or mineralfiller, whatever its colour and its origin (natural or synthetic), alsoknown as “white filler”, “clear filler”, indeed even “non-black filler”,in contrast to carbon black, capable of reinforcing by itself alone,without means other than an intermediate coupling agent, a rubbercomposition intended for the manufacture of tyres, in other wordscapable of replacing, in its reinforcing role, a conventional tyre-gradecarbon black. Such a filler is generally characterized, in a known way,by the presence of hydroxyl (—OH) groups at its surface.

The physical state in which the reinforcing inorganic filler is providedis not important, whether it is in the form of a powder, of micropearls,of granules, of beads or any other appropriate densified form. Ofcourse, “reinforcing inorganic filler” is also understood to meanmixtures of different reinforcing inorganic fillers, in particular ofhighly dispersible siliceous and/or aluminous fillers as describedbelow.

Mineral fillers of the siliceous type, especially silica (SiO₂), or ofthe aluminous type, especially alumina (Al₂O₃), are suitable inparticular as reinforcing inorganic fillers. The silica used can be anyreinforcing silica known to a person skilled in the art, in particularany precipitated or fumed silica exhibiting a BET specific surface and aCTAB specific surface both of less than 450 m²/g, preferably from 30 to400 m²/g. Mention will be made, as highly dispersible precipitatedsilicas (“HDSs”), for example, of the Ultrasil 7000 and Ultrasil 7005silicas from Evonik, the Zeosil 1165MP, 1135MP and 1115MP silicas fromRhodia, the Hi-Sil EZ150G silica from PPG, the Zeopol 8715, 8745 and8755 silicas from Huber or the silicas with a high specific surface asdescribed in Application WO 03/16837.

Finally, a person skilled in the art will understand that, as fillerequivalent to the reinforcing inorganic filler described in the presentsection, use might be made of a reinforcing filler of another nature, inparticular organic nature, provided that this reinforcing filler iscovered with an inorganic layer, such as silica, or else comprisesfunctional sites, in particular hydroxyl sites, at its surface whichrequire the use of a coupling agent in order to establish the bondbetween the filler and the elastomer.

Preferably, the content of total reinforcing filler (carbon black and/orreinforcing inorganic filler, such as silica) is within a rangeextending from 5 to 120 phr, more preferably from 5 to 100 phr and morepreferably still from 5 to 90 phr.

Preferably, the content of total reinforcing filler is within a rangeextending from 10 to 120 phr, more preferably from 10 to 100 phr andmore preferably still from 10 to 90 phr.

More preferably, the content of total reinforcing filler is within arange extending from 20 to 120 phr, more preferably from 20 to 100 phrand more preferably still from 20 to 90 phr.

More preferably still, the content of total reinforcing filler is withina range extending from 30 to 120 phr, more preferably from 30 to 100 phrand more preferably still from 30 to 90 phr.

The carbon black can advantageously constitute the sole reinforcingfiller or the predominant reinforcing filler. Of course, it is possibleto use just one carbon black or a blend of several carbon blacks ofdifferent ASTM grades. The carbon black can also be used as a blend withother reinforcing fillers and in particular reinforcing inorganicfillers as described above, in particular silica.

When an inorganic filler (for example silica) is used in the rubbercomposition, alone or as a blend with carbon black, its content iswithin a range from 0 to 70 phr, preferably from 0 to 50 phr, inparticular also from 5 to 70 phr, and more preferably still thisproportion varies from 5 to 50 phr, particularly from 5 to 40 phr.

Preferably, the rubber composition comprises various additives.

The rubber compositions can also comprise all or a portion of the usualadditives customarily used in elastomer compositions intended for themanufacture of tyres, such as, for example, plasticizers or extendingoils, whether the latter are aromatic or non-aromatic in nature,pigments, protective agents, such as antiozone waxes, chemicalantiozonants or antioxidants, antifatigue agents or indeed even adhesionpromoters.

Preferably, the rubber composition comprises a crosslinking system, morepreferably a vulcanization system.

The vulcanization system comprises a sulfur-donating agent, for examplesulfur.

Preferably, the vulcanization system comprises vulcanization activators,such as zinc oxide and stearic acid.

Preferably, the vulcanization system comprises a vulcanizationaccelerator and/or a vulcanization retarder.

The sulfur or sulfur-donating agent is used at a preferred contentwithin a range from 0.5 to 10 phr, more preferably within a range from0.5 to 8.0 phr. The combined vulcanization accelerators, retarders andactivators are used at a preferred content within a range from 0.5 to 15phr. The vulcanization activator or activators is or are used at apreferred content within a range from 0.5 to 12 phr.

The crosslinking system proper is preferably based on sulfur and on aprimary vulcanization accelerator, in particular on an accelerator ofthe sulfenamide type. Additional to this vulcanization system arevarious known secondary vulcanization accelerators or vulcanizationactivators, such as zinc oxide, stearic acid, guanidine derivatives (inparticular diphenylguanidine), and the like.

Use may be made, as (primary or secondary) accelerator, of any compoundcapable of acting as accelerator for the vulcanization of dieneelastomers in the presence of sulfur, in particular accelerators of thethiazole type, and also their derivatives, and accelerators of thiuramtype and of zinc dithiocarbamate type. These accelerators are morepreferably selected from the group consisting of 2-mercaptobenzothiazoledisulfide (abbreviated to “M BTS”),N-cyclohexyl-2-benzothiazolesulfenamide (abbreviated to “CBS”),N,N-dicyclohexyl-2-benzothiazolesulfenamide (abbreviated to “DCBS”),N-(tert-butyl)-2-benzothiazolesulfenamide (abbreviated to “TBBS”),N-(tert-butyl)-2-benzothiazolesulfenimide (abbreviated to “TBSI”), zincdibenzyldithiocarbamate (abbreviated to “ZBEC”) and the mixtures ofthese compounds. Preferably, use is made of a primary accelerator of thesulfenamide type.

In one embodiment, the rubber composition is in the cured, that is tosay vulcanized, state. In other embodiments, the composition is in theraw, that is to say non-vulcanized, state, the crosslinked resin havingbeen added subsequently to the non-vulcanized composition.

In one embodiment, the resin not yet having crosslinked, the rubbercomposition comprises:

A1) at least one aromatic compound comprising at least one aromatic ringbearing at least two functional groups, one of these functional groupsbeing a hydroxymethyl functional group and the other being an aldehydefunctional group or a hydroxymethyl functional group; andA2) at least one phenolic compound chosen from:

-   -   A21) at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted,    -   A22) at least one aromatic monophenol comprising at least one        six-membered aromatic ring bearing a single hydroxyl functional        group,        -   the two positions ortho to the hydroxyl functional group            being unsubstituted or        -   at least one position ortho to and the position para to the            hydroxyl functional group being unsubstituted,            and their mixtures.

Preferably, in this embodiment, the composition is in the raw, that isto say non-vulcanized, state.

Preferably, the rubber composition can be used in the tyre in the formof a layer. Layer is understood to mean any three-dimensional element,having any shape and thickness, in particular as sheet, strip or otherelement having any cross-section, for example rectangular or triangular.

Of course, all the characteristics relating to the aromatic polyphenoland to the compound of the composition comprising the resin also applyto the composition comprising the aromatic polyphenol and the compoundwhich are not crosslinked in the resin state.

Rubber Composite According to the Invention

The rubber composite is reinforced with at least one reinforcing elementembedded in the rubber composition according to the invention.

This rubber composite can be prepared according to a process comprisingat least the following steps:

-   -   during a first step, combining at least one reinforcing element        with a rubber composition (or elastomer; the two terms are        synonyms) according to the invention, in order to form a rubber        composite reinforced with the reinforcing element;    -   then, during a second step, crosslinking by curing, for example        by vulcanization, preferably under pressure, the composite thus        formed.

Mention may be made, among reinforcing elements, of textile, metallic ortextile-metal hybrid reinforcing elements.

“Textile” is understood to mean, in a way well known to a person skilledin the art, any material made of a substance other than a metallicsubstance, whether natural or synthetic, which is capable of beingtransformed into thread or fibre by any appropriate transformationprocess. Mention may be made, for example, without the examples belowbeing limiting, of a polymer spinning process, such as, for example,melt spinning, solution spinning or gel spinning.

This textile material can consist of a thread or fibre, or also of afabric produced from threads or fibres, for example a woven fabric withwarp threads and weft threads, or else a twill fabric with crossthreads.

This textile material of the invention is preferably selected from thegroup consisting of monofilaments (or individual threads), multifilamentfibres, assemblies of such threads or fibres, and the mixtures of suchmaterials. It is more particularly a monofilament, a multifilament fibreor a folded yarn.

Thread or fibre is generally understood to mean any elongate element ofgreat length relative to its cross section, whatever the shape, forexample circular, oblong, rectangular, square, or even flat, of thiscross section, it being possible for this thread to be straight or notstraight, for example twisted or wavy. The largest dimension of itscross section is preferably less than 5 mm, more preferably less than 3mm.

This thread or fibre may take any known form. For example, it may be anindividual monofilament of large diameter (for example and preferablyequal to or greater than 50 μm), a multifilament fibre (consisting of aplurality of individual filaments of small diameter, typically less than30 μm), a textile folded yarn or cord formed from several textile fibresor monofilaments twisted or cabled together, or else an assembly, groupor row of threads or fibres, such as, for example, a band or stripcomprising several of these monofilaments, fibres, folded yarns or cordsgrouped together, for example aligned along a main direction, whetherstraight or not.

The textile materials can be made of organic or polymeric substance,such as made of inorganic substance.

Mention will be made, as examples of inorganic substances, of glass orcarbon.

The invention is preferably implemented with materials made of polymericsubstance, of both the thermoplastic and non-thermoplastic type.

Mention will be made, as examples of polymeric substances of thenon-thermoplastic type, for example, of aramid (aromatic polyamide) andcellulose, both natural and artificial, such as cotton, rayon, flax orhemp.

Mention will preferably be made, as examples of polymeric substances ofthe thermoplastic type, of aliphatic polyamides and of polyesters.Mention may in particular be made, among the aliphatic polyamides, ofthe polyamides PA-4,6, PA-6, PA-6,6, PA-11 or PA-12. Mention may bemade, among the polyesters, for example, of PET (polyethyleneterephthalate), PEN (polyethylene naphthalate), PBT (polybutyleneterephthalate), PBN (polybutylene naphthalate), PPT (polypropyleneterephthalate) and PPN (polypropylene naphthalate).

By definition, metallic is understood to mean one or more threadlikeelements composed predominantly (that is to say, for more than 50% ofits weight) or entirely (for 100% of its weight) of a metallic material.Preferably, the metallic material is steel, more preferably made ofpearlitic (or ferritic-pearlitic) carbon steel advantageously comprisingbetween 0.4% and 1.2% by weight of carbon.

The metallic reinforcing element can be a monofilament, a cordcomprising several metallic monofilaments or a multistrand ropecomprising several cords, then referred to as strands.

In the preferred case where the reinforcing element comprises severalmetallic monofilaments or several strands, the metallic monofilaments orthe strands are assembled by twisting or braiding. It should beremembered that there exist two possible techniques for assembling:

-   -   either by twisting: the metallic monofilaments or the strands        undergo both a collective twist and an individual twist about        their own axis, which generates an untwisting torque on each of        the monofilaments or strands;    -   or by braiding: the metallic monofilaments or the strands only        undergo a collective twist and do not undergo an individual        twist about their own axis.

Optionally, the reinforcing element comprises several monofilaments andis of the rubberized in situ type, that is to say that the reinforcingelement is rubberized from the inside, during its actual manufacture, bya filling rubber. Such metallic threadlike elements are known to aperson skilled in the art. The composition of the filling rubber may ormay not be identical to the rubber composition in which the reinforcingelement is embedded.

Each reinforcing element, when it is textile, is preferably coated witha layer of an adhesive composition or adhesive. The adhesive used is,for example, of the RFL (resorcinol/formaldehyde latex) type or, forexample, as described in the publications WO2013017421, WO2013017422,WO2013017423 or else WO2015007642. Thus, the rubber compositionaccording to the invention is in direct contact with the adhesivecomposition. The adhesive composition is interposed between the rubbercomposition according to the invention and the reinforcing element.

Tyre According to the Invention

Such tyres are, for example, those intended to equip motor vehicles ofpassenger type, SUVs (“Sport Utility Vehicles”), two-wheel vehicles (inparticular bicycles and motorcycles), aircraft, as for industrialvehicles chosen from vans, “heavy-duty” vehicles—that is to say,underground trains, buses, heavy road transport vehicles (lorries,tractors, trailers) or off-road vehicles, such as heavy agriculturalvehicles or earthmoving equipment—, or other transportation or handlingvehicles.

By way of example, the appended FIG. 1 represents very diagrammatically(without observing a specific scale) a radial section of a tyre inaccordance with the invention for a vehicle of the heavy-duty type.

This tyre 1 comprises a crown 2 reinforced by a crown reinforcement orbelt 6, two sidewalls 3 and two beads 4, each of these beads 4 beingreinforced with a bead wire 5. The crown 2 is surmounted by a tread, notrepresented in this diagrammatic figure. A carcass reinforcement 7 iswound around the two bead wires 5 in each bead 4, the turn-up 8 of thisreinforcement 7 being, for example, positioned towards the outside ofthe tyre 1, which is here represented fitted onto its wheel rim 9. Thecarcass reinforcement 7 is, in a way known per se, composed of at leastone ply reinforced by “radial” cords, for example of metal, that is tosay that these cords are positioned virtually parallel to one anotherand extend from one bead to the other so as to form an angle of between80° and 90° with the median circumferential plane (plane perpendicularto the axis of rotation of the tyre which is located halfway between thetwo beads 4 and passes through the middle of the crown reinforcement 6).

This tyre 1 of the invention has, for example, the characteristic thatat least a crown reinforcement 6 and/or its carcass reinforcement 7comprises a rubber composition or a composite according to theinvention. Of course, the invention relates to the objects describedabove, namely the rubber composite and the tyre, both in the raw state(before curing or vulcanization) and in the cured state (after curing).

Process for the Manufacture of the Composition According to theInvention

The manufacturing process described above and below makes it possible tomanufacture the composition according to the invention.

The rubber composition can be manufactured in appropriate mixers usingtwo successive preparation phases well known to a person skilled in theart:

-   -   a first phase of thermomechanical working or kneading        (“non-productive” phase) at high temperature, up to a maximum        temperature of between 110° C. and 190° C., preferably between        130° C. and 180° C.,    -   followed by a second phase of mechanical working (“productive”        phase) down to a lower temperature, typically of less than 110°        C., for example between 40° C. and 100° C., during which        finishing phase the crosslinking system is incorporated.

In one embodiment, the process comprises the following steps:

-   -   incorporating a reinforcing filler in a diene elastomer, during        a first step (referred to as “non-productive” step), everything        being kneaded thermomechanically (for example, in one or more        goes) until a maximum temperature of between 110° C. and 190° C.        is reached;    -   cooling the combined mixture to a temperature of less than 110°        C.;    -   subsequently incorporating, during a second step (referred to as        “productive” step), a crosslinking system, the aromatic compound        A1 and the phenolic compound A2;    -   kneading everything up to a maximum temperature of less than        110° C.

By way of example, the non-productive phase is carried out in a singlethermomechanical step during which, in a first step, all the necessarybase constituents (diene elastomer, reinforcing filler,) are introducedinto an appropriate mixer, such as an ordinary internal mixer, and then,in a second step, for example after kneading for one to two minutes, theother additives, optional additional agents for covering the filler oroptional additional processing aids, with the exception of thecrosslinking system, are introduced. The total duration of the kneading,in this non-productive phase, is preferably between 1 and 15 min.

After cooling the mixture thus obtained, the crosslinking system, thearomatic compound A1 and the phenolic compound A2 are then incorporatedin an external mixer, such as an open mill, maintained at a lowtemperature (for example between 40° C. and 100° C.). The combinedmixture is then mixed (productive phase) for a few minutes, for examplebetween 2 and 15 min.

The final composition thus obtained in the raw state can subsequently becalendered, for example in the form of a sheet or of a plaque, inparticular for laboratory characterization, or else extruded, forexample in order to form a rubber profiled element used in themanufacture of a tyre.

Then, after an optional step of assembling together several compositionsformed as plies or strips in the form of a composite or of a raw tyreblank, a step of crosslinking, for example a step of vulcanization orcuring, the composition, the composite or the blank is carried out,during which the resin based on the aromatic compound and on thearomatic polyphenol is crosslinked. The crosslinking step, in thisinstance the vulcanization or curing step, is carried out at atemperature of greater than or equal to 120° C., preferably of greaterthan or equal to 140° C. The composition is obtained in the cured state.

In another embodiment, the process comprises the following steps:

-   -   incorporating a reinforcing filler, the phenolic compound A2 and        the aromatic compound A1 in an elastomer, during a first step,        everything being kneaded thermomechanically until a maximum        temperature of between 110° C. and 190° C. is reached;    -   cooling the combined mixture to a temperature of less than 110°        C.;    -   subsequently incorporating, during a second step, a crosslinking        system;    -   kneading everything at a temperature of less than 110° C.

The invention and its advantages will be easily understood in the lightof the exemplary embodiments which follow.

Exemplary Embodiments of the Invention and Comparative Tests

These tests demonstrate that:

-   -   the stiffness of the rubber compositions according to the        invention is greatly increased with respect to a rubber        composition devoid of reinforcing resin,    -   the stiffness of the rubber composition is similar (composition        C1) or greatly improved (composition C2) with respect to a        rubber composition using a conventional reinforcing resin based        on a methylene acceptor with HMT or H3M as methylene donor        (composition T1),    -   the stiffness of the rubber composition according to the        invention at high temperatures, in particular for temperatures        ranging up to 150° C., is improved with respect to a rubber        composition devoid of reinforcing resin,    -   the resin of the composition according to the invention is        devoid of formaldehyde and does not generate any formaldehyde        during its formation.

For this, several rubber compositions, denoted T0 to T3, C1 and C2below, were prepared as indicated above and are collated in the appendedTable 1 below.

All the compositions T0 to T3, C1 and C2 have a shared part in theirformulations (expressed in phr, parts by weight per hundred parts ofelastomer): 100 phr of natural rubber, 75 phr of carbon black N326, 1.5phr of N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine, 1.5 phr ofstearic acid, 5 phr of ZnO, 1 phr ofN-(tert-butyl)-2-benzothiazolesulfamide and 2.5 phr of insoluble sulfur20H.

The composition T0 does not comprise any reinforcing resin added to thisshared part.

In addition to the shared part, the composition T1 comprises areinforcing resin based on hexamethylenetetramine (1.6 phr) and on apre-condensed phenolic resin (4 phr). The composition T1 represents aconventional composition of the state of the art exhibiting a greaterstiffness than that of the composition T0.

In addition to the shared part, each composition T2 and T3 comprises 14phr of aromatic polyphenol A21 and 14 phr of benzaldehyde.

In addition to the shared part, the composition C1 comprises 14 phr ofaromatic polyphenol A21 and 14 phr of aromatic compound A1.

In addition to the shared part, the composition C2 comprises 14 phr ofaromatic polyphenol A21 and 28 phr of aromatic compound A1.

The compositions T0 to T3 are not in accordance with the invention,unlike compositions C1 and C2, which are in accordance with theinvention.

In the raw state, each rubber composition T2 and T3, not in accordancewith the invention, comprises:

-   -   at least one aromatic aldehyde, in this instance benzaldehyde,        and    -   at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted.

In the cured state, each rubber composition T2 and T3, not in accordancewith the invention, comprises a phenol/aldehyde resin based:

-   -   on at least one aromatic aldehyde, in this instance        benzaldehyde, and    -   on at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted.

In the raw state, each rubber composition C1 and C2 according to theinvention comprises:

-   -   at least one aromatic compound comprising at least one aromatic        ring bearing at least two functional groups, one of these        functional groups being a hydroxymethyl functional group and the        other being an aldehyde functional group or a hydroxymethyl        functional group; and    -   at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted.

In the cured state, each rubber composition C1 and C2 according to theinvention comprises a resin based:

-   -   on at least one aromatic compound comprising at least one        aromatic ring bearing at least two functional groups, one of        these functional groups being a hydroxymethyl functional group        and the other being an aldehyde functional group or a        hydroxymethyl functional group; and    -   on at least one aromatic polyphenol comprising at least one        aromatic ring bearing at least two hydroxyl functional groups in        the meta position with respect to one another, the two positions        ortho to at least one of the hydroxyl functional groups being        unsubstituted.

The aromatic polyphenol of the resin of each composition T2, T3, C1 andC2 is selected from the group consisting of resorcinol, phloroglucinol,2,2′,4,4′-tetrahydroxydiphenyl sulfide,2,2′,4,4′-tetrahydroxybenzophenone, resins pre-condensed from thesephenols and the mixtures of these compounds.

The aromatic polyphenol of the composition T1 is a resin pre-condensedfrom resorcinol and formaldehyde.

The aromatic polyphenol of the composition T3 comprises a singlearomatic ring, in this instance a benzene ring, bearing two, and onlytwo, hydroxyl functional groups in the meta position with respect to oneanother. In the case in point, it is resorcinol.

The polyphenol of each composition T2, C1 and C2 comprises a singlearomatic ring, in this instance a benzene ring, bearing three, and onlythree, hydroxyl functional groups in the meta position with respect toone another. In the case in point, it is phloroglucinol.

For the aromatic polyphenols of each composition T2, T3, C1 and C2, theremainder of the aromatic ring of the aromatic polyphenol isunsubstituted. In particular, the two positions ortho to each hydroxylfunctional group are unsubstituted.

The aromatic compound of each composition C1 and C2 according to theinvention is 5-(hydroxymethyl)furfural.

Preparation Process

In a first step, the reinforcing filler was incorporated in anelastomer, everything being kneaded thermomechanically until a maximumtemperature of between 110° C. and 190° C. was reached. The combinedmixture was then cooled to a temperature of less than 110° C.Subsequently, during a second step, the crosslinking system, apre-condensed resin and a methylene donor (T1) or the aromaticpolyphenol and 5-(hydroxymethyl)furfural (C1, C2) or the aromaticpolyphenol and benzaldehyde (T2, T3) were incorporated. At the end ofthis second step, the mixture was heated to 150° C. until the maximumrheometric torque was obtained, in order to vulcanize the compositionand crosslink the resin. The stiffness at 23° C. of the composition wasthen characterized during a tensile test.

Characterization of the Stiffness at High Temperature—Maximum RheometricTorque

The measurements are carried out at 150° C. with an oscillating discrheometer, according to Standard DIN 53529—Part 3 (June 1983). Thechange in the rheometric torque as a function of time describes thechange in the stiffening of the composition as a result of thevulcanization and of the crosslinking of the resin. From the change inthe rheometric torque, the maximum rheometric torque Cmax given in Table1 is determined. The higher the maximum rheometric torque Cmax, the morethe composition exhibits a stiffness which can be maintained at hightemperature. Each curve representing the change in the rheometric torquerespectively of the compositions C1 and C2 and also those representingthe change in the rheometric torque of the compositions T0 to T3 havebeen represented in FIGS. 2 and 3.

The higher the maximum rheometric torque Cmax, the more the compositionexhibits a stiffness which can be maintained at high temperature.

Characterization of the Stiffness at 23° C.—Tensile Test

These tests make it possible to determine the elasticity stresses andthe properties at break. Unless otherwise indicated, they are carriedout in accordance with Standard ASTM D 412 of 1998 (test specimen C).The “nominal” secant moduli (or apparent stresses, in MPa) at 10%elongation (denoted “MA10”) are measured in second elongation (i.e.,after an accommodation cycle). All these tensile measurements arecarried out under standard temperature and relative humidity conditions,according to Standard ASTM D 1349 of 1999, and are given in Table 1.

First of all, the results of Table 1 show that the use of a reinforcingresin of the state of the art (T1) makes it possible to obtain a betterstiffness at 23° C. and a better retention of this stiffness at highertemperatures than for a composition devoid of reinforcing resin (T0).However, the stiffness at 23° C. of the composition T1 is significantlylower than that of the composition C2 according to the invention andsimilar to that of the composition C1 according to the invention.

Furthermore, the results of Table 1 show that the use of an aromaticaldehyde comprising a benzene ring bearing a single aldehyde functionalgroup (T2 and T3) results in a fall in or at best a maintenance of thestiffness at higher temperatures with respect to the composition T0,unlike the aromatic compounds of compositions C1 and C2, which result inan increase in the maintenance of the stiffness at higher temperatures.These results are relatively unexpected for a person skilled in the artin view of the fact that, a priori, the aromatic compound ofcompositions C1 and C2 exhibits a lower reactivity than that of thearomatic monoaldehyde of compositions T2 and T3.

The invention is not limited to the embodiments described above.

In other embodiments, it will be possible to envisage for the resin tobe based on one or more aromatic compounds A1 and on one or morephenolic compounds A2 in accordance with the invention and, in additionto these constituents, based on one or more additional aldehydes not inaccordance with the invention and/or one or more additional aromaticpolyphenols or monophenols not in accordance with the invention.

TABLE 1 Compo- Methylene MA10 Cmax sition donor Phenol (MPa) (dN · m) T0/ / 6.7 16 T1 Hexamethylene- SRF resin (2) 16.5 43 tetramine (1) Compo-Aromatic Aromatic MA10 Cmax sition aldehyde polyphenol (MPa) (dN · m) T2Benzaldehyde (3) Phloroglucinol (4) 14.7 14 T3 Benzaldehyde (3)Resorcinol (5) 12.1 7 Compo- Aromatic Aromatic MA10 Cmax sition compoundpolyphenol (MPa) (dN · m) C1 5-(Hydroxymethyl)- Phloroglucinol (4) 15.124 furfural (6) C2 5-(Hydroxymethyl)- Phloroglucinol (4) 31 33 furfural(6) (1) Hexamethylenetetramine (from Sigma-Aldrich; of ≥99% purity); (2)Pre-condensed resin SRF 1524 (from Schenectady; 75% diluted); (3)Benzaldehyde (from Sigma-Aldrich; of ≥99.5% purity); (4) Phloroglucinol(from Alfa Aesar; of 99% purity); (5) Resorcinol (from Sumitomo; of99.5% purity); (6) 5-(Hydroxymethyl)furfural (from Aldrich; of ≥99%purity)

1.-25. (canceled)
 26. A rubber composition comprising at least one resinbased on: (A1) at least one aromatic compound comprising at least onearomatic ring bearing at least two functional groups, one of thefunctional groups being a hydroxymethyl functional group and another ofthe functional groups being an aldehyde functional group or ahydroxymethyl functional group; and (A2) at least one phenolic compoundselected from the group consisting of: (A21) at least one aromaticpolyphenol comprising at least one aromatic ring bearing at least twohydroxyl functional groups in the meta position with respect to oneanother, the two positions ortho to at least one of the hydroxylfunctional groups being unsubstituted; (A22) at least one aromaticmonophenol comprising at least one six-membered aromatic ring bearing asingle hydroxyl functional group, the two positions ortho to thehydroxyl functional group being unsubstituted or at least one positionortho to and the position para to the hydroxyl functional group beingunsubstituted; and mixtures thereof.
 27. The rubber compositionaccording to claim 26, wherein the aromatic compound (A1) corresponds tothe general formula (II):

where B represents CHO or CH₂OH, X represents O, NR₁, NO, S, SO, SO₂ orSR₂R₃, R₁ represents a hydrogen or an alkyl, aryl, arylalkyl, alkylarylor cycloalkyl group, and R₂ and R₃ each represent, independently of oneanother, a hydrogen or an alkyl, aryl, arylalkyl, alkylaryl orcycloalkyl group.
 28. The rubber composition according to claim 26,wherein the aromatic compound (A1) is selected from the group consistingof 5-(hydroxymethyl)furfural, 2,5-di(hydroxymethyl)furan and mixturesthereof.
 29. The rubber composition according to claim 26, wherein thearomatic ring of the aromatic polyphenol bears three hydroxyl functionalgroups in the meta position with respect to one another.
 30. The rubbercomposition according to claim 26, wherein, on the aromatic ring of thearomatic polyphenol, the two positions ortho to each hydroxyl functionalgroup are unsubstituted.
 31. The rubber composition according to claim26, wherein a remainder of the aromatic ring of the aromatic polyphenolis unsubstituted.
 32. The rubber composition according to claim 26,wherein the aromatic polyphenol comprises several aromatic rings, atleast two of them each bearing at least two hydroxyl functional groupsin the meta position with respect to one another, the two positionsortho to at least one of the hydroxyl functional groups of at least onearomatic ring being unsubstituted.
 33. The rubber composition accordingto claim 32, wherein at least one of the aromatic rings of the aromaticpolyphenol bears three hydroxyl functional groups in the meta positionwith respect to one another.
 34. The rubber composition according toclaim 26, wherein each aromatic ring of the aromatic polyphenol is abenzene ring.
 35. The rubber composition according to claim 26, whereinthe aromatic polyphenol is selected from the group consisting ofresorcinol, phloroglucinol, 2,2′,4,4′-tetrahydroxydiphenyl sulfide,2,2′,4,4′-tetrahydroxybenzophenone and mixtures thereof.
 36. The rubbercomposition according to claim 26, wherein the aromatic polyphenol is apre-condensed resin based on: (a) at least one polyphenol comprising atleast one aromatic ring bearing at least two hydroxyl functional groupsin the meta position with respect to one another, the two positionsortho to at least one of the hydroxyl functional groups beingunsubstituted; and (b) at least one compound capable of reacting withthe polyphenol comprising at least one aldehyde functional group and/orat least one compound capable of reacting with the polyphenol comprisingat least two hydroxymethyl functional groups borne by an aromatic ring.37. The rubber composition according to claim 26 further comprising adiene elastomer selected from the group consisting of polybutadienes,synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprenecopolymers and mixtures thereof.
 38. The rubber composition according toclaim 26, wherein the rubber composition is in the cured state.
 39. Therubber composition, wherein the rubber composition comprises: (A1) atleast one aromatic compound comprising at least one aromatic ringbearing at least two functional groups, one of these functional groupsbeing a hydroxymethyl functional group and the other being an aldehydefunctional group or a hydroxymethyl functional group; and (A2) at leastone phenolic compound selected from the group consisting of: (A21) atleast one aromatic polyphenol comprising at least one aromatic ringbearing at least two hydroxyl functional groups in the meta positionwith respect to one another, the two positions ortho to at least one ofthe hydroxyl functional groups being unsubstituted; (A22) at least onearomatic monophenol comprising at least one six-membered aromatic ringbearing a single hydroxyl functional group, the two positions ortho tothe hydroxyl functional group being unsubstituted or at least oneposition ortho to and the position para to the hydroxyl functional groupbeing unsubstituted; and mixtures thereof.
 40. The rubber compositionaccording to claim 39, wherein the rubber composition is in the rawstate.
 41. A process for the manufacture of a rubber composition in theraw state, the process comprising the step of: mixing at least oneelastomer, (A1) at least one aromatic compound comprising at least onearomatic ring bearing at least two functional groups, one of thesefunctional groups being a hydroxymethyl functional group and the otherbeing an aldehyde functional group or a hydroxymethyl functional group,and (A2) at least one phenolic compound selected from the groupconsisting of: (A21) at least one aromatic polyphenol comprising atleast one aromatic ring bearing at least two hydroxyl functional groupsin the meta position with respect to one another, the two positionsortho to at least one of the hydroxyl functional groups beingunsubstituted; (A22) at least one aromatic monophenol comprising atleast one six-membered aromatic ring bearing a single hydroxylfunctional group, the two positions ortho to the hydroxyl functionalgroup being unsubstituted or at least one position ortho to and theposition para to the hydroxyl functional group being unsubstituted; andmixtures thereof.
 42. A process for the manufacture of a rubbercomposition in the cured state, the process comprising the steps of:manufacturing a rubber composition in the raw state by mixing (A1) atleast one aromatic compound comprising at least one aromatic ringbearing at least two functional groups, one of these functional groupsbeing a hydroxymethyl functional group and the other being an aldehydefunctional group or a hydroxymethyl functional group, and (A2) at leastone phenolic compound selected from the group consisting of: (A21) atleast one aromatic polyphenol comprising at least one aromatic ringbearing at least two hydroxyl functional groups in the meta positionwith respect to one another, the two positions ortho to at least one ofthe hydroxyl functional groups being unsubstituted; (A22) at least onearomatic monophenol comprising at least one six-membered aromatic ringbearing a single hydroxyl functional group, the two positions ortho tothe hydroxyl functional group being unsubstituted or at least oneposition ortho to and the position para to the hydroxyl functional groupbeing unsubstituted; and mixtures thereof; shaping the rubbercomposition in the raw state; and crosslinking the rubber compositionduring which a resin based on the phenolic compound (A2) and on thearomatic compound (A1) is crosslinked.
 43. A rubber composition obtainedby the process of claim
 42. 44. A rubber composite reinforced with atleast one reinforcing element embedded in the rubber composition ofclaim
 43. 45. A tire comprising a rubber composition according to claim26.